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Vue normale

Reçu — 12 mars 2026 ⏭

On a trouvé la source des explosions les plus brillantes de l’Univers

✇Numerama.com - Magazine
Par : Hugo Ruher
12 mars 2026 à 12:31

Visualisation d'un magnétar

Pour la première fois, des astronomes ont pu observer la naissance d'un magnétar, une sorte d'étoile à neutrons très particulière. Ces nouvelles données confirment que ces astres sont la cause d'explosions incroyablement brillantes et toujours mystérieuses.

Reçu — 11 mars 2026 ⏭
Reçu — 10 mars 2026 ⏭

Cette sonde va retomber sur Terre 8 ans plus tôt que prévu, et c’est à cause du Soleil

✇Numerama.com - Magazine
Par : Hugo Ruher
10 mars 2026 à 10:36

Les deux sondes Van Allen Probes

Une des sondes de la mission Van Allen Probes va revenir sur Terre. Ou plutôt, elle va se désintégrer en plongeant dans l'atmosphère terrestre. Une fin de vie classique pour un satellite en orbite depuis 14 ans, mais qui se produit bien plus tôt que ce que prévoyaient les modèles.

Startup Wants To Launch a Space Mirror

✇Slashdot
Par : BeauHD
10 mars 2026 à 07:00
A startup called Reflect Orbital wants to launch thousands of mirror-bearing satellites to reflect sunlight onto Earth at night and "power solar farms after sunset, provide lighting for rescue workers and illuminate city streets, among other things," reports the New York Times. From the report: It is an idea seemingly out of a sci-fi movie, but the company, Reflect Orbital of Hawthorne, Calif., could soon receive permission to launch its first prototype satellite with a 60-foot-wide mirror. The company has applied to the Federal Communications Commission, which issues the licenses needed to deploy satellites. If the F.C.C. approves, the test satellite could get a ride into orbit as soon as this summer. The F.C.C.'s public comment period on the application closes on Monday. "We're trying to build something that could replace fossil fuels and really power everything," Ben Nowack, Reflect Orbital's chief executive, said in an interview. The company has raised more than $28 million from investors. [...] Reflect Orbital's first prototype, which will be roughly the size of a dorm fridge, is almost complete. Once in space, about 400 miles up, the test satellite would unfurl a square mirror nearly 60 feet wide. That would bounce sunlight to illuminate a circular patch about three miles wide on the Earth's surface. Someone looking up would see a dot in the sky about as bright as a full moon. Two more prototypes could follow within a year. By the end of 2028, Reflect Orbital hopes to launch 1,000 larger satellites, and 5,000 of them by 2030. The largest mirrors are planned to be nearly 180 feet wide, reflecting as much light as 100 full moons. The company said its goal was to deploy the full constellation of 50,000 satellites by 2035. How much does it cost to order sunlight at night? Mr. Nowack said the company would charge about $5,000 an hour for the light of one mirror if a customer signed an annual contract for 1,000 hours or more. Lighting for one-time events and emergencies, which might require numerous satellites and more effort to coordinate, would be more expensive. For solar farms, he envisions splitting revenue from the electricity generated by the additional hours of light.

Read more of this story at Slashdot.

Reçu — 9 mars 2026 ⏭

New SETI Study: Why We Might Have Been Missing Alien Signals

✇Slashdot
Par : EditorDavid
9 mars 2026 à 11:34
After decades of searching for extraterrestrial intelligence, the nonprofit SETI Foundation has an announcement. "A new study by researchers at the SETI Institute suggests stellar 'space weather' could make radio signals from extraterrestrial intelligence harder to detect." Stellar activity and plasma turbulence near a transmitting planet can broaden an otherwise ultra-narrow signal, spreading its power across more frequencies and making it more difficult to detect in traditional narrowband searches. For decades, many SETI experiments have focused on identifying spikes in frequency — signals unlikely to be produced by natural astrophysical processes. But the new research highlights an overlooked complication: even if an extraterrestrial transmitter produces a perfectly narrow signal, it may not remain narrow by the time it leaves its home system... "If a signal gets broadened by its own star's environment, it can slip below our detection thresholds, even if it's there, potentially helping explain some of the radio silence we've seen in technosignature searches," said Dr. Vishal Gajjar, Astronomer at the SETI Institute and lead author of the paper. The researchers created "a practical framework for estimating how much broadening could occur for different types of stars" — and accounting for space weather — by "using radio transmissions from spacecraft in our own solar system, then extrapolated to other stellar environments." The study's co-author (a SETI Institute research assistant) suggests this coud lead to better-targetted SETI searches. (M-dwarf stars — about 75% of stars in the Milky Way — actually have the highest likelihood that narrowband signals would get broadened before leaving their system...)

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Qu’est-ce qu’une météorite, comment la reconnaître, et quelle est sa valeur ?

✇Numerama.com - Magazine
Par : Nelly Lesage
9 mars 2026 à 09:35

Les météorites sont des roches extraterrestres, prisées des collectionneurs et des férus d'espace. Mais, qu'est-ce qu'une météorite exactement ? Quelle différence entre météorite, météore, météoroïde et bolide ?

Une sonde spatiale européenne est perdue dans l’espace, et personne n’arrive à la contacter

✇Numerama.com - Magazine
Par : Hugo Ruher
9 mars 2026 à 09:31

La mission Proba 3 ne répond plus. Cette sonde lancée par l'Agence spatiale européenne (ESA) fin 2024 ne montre aucun signe de vie. Elle devait tester des manœuvres de proximité, mais suite à une anomalie, il est impossible de communiquer avec elle.

La fusée géante Starship passe le test du froid extrême, en attendant l’épreuve du feu

✇Numerama.com - Magazine
Par : Julien Lausson
9 mars 2026 à 09:03

SpaceX poursuit sa campagne de calibrage pour le prochain vol de la fusée Starship. Ce week-end, des tests cryogéniques et de résistance à la pression ont eu lieu. Le décollage reste envisagé dans les prochaines semaines.

Scientists Just Doubled Our Catalog of Black Hole and Neutron Star Collisions

✇Slashdot
Par : EditorDavid
9 mars 2026 à 04:34
Colliding black holes were detected through spacetime ripples for the first time in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO), notes Space.com: Since then, LIGO and its partner gravitational wave detectors Virgo in Italy and KAGRA (Kamioka Gravitational Wave Detector) in Japan have detected a multitude of gravitational waves from colliding black holes, merging neutron stars, and even the odd "mixed merger" between a black hole and a neutron star... During the first three observing runs of LIGO, Virgo and KAGRA, scientists had only "heard" 90 potential gravitational wave sources. But now they've published new data from the LIGO-Virgo-KAGRA (LVK) Collaboration that includes 128 more gravitatational wave sources — some incredibly distant: [Gravitational-Wave Transient Catalog-4.0, or GWTC-4] was collected during the fourth observational run of these gravitational wave detectors, which was conducted between May 2023 and Jan. 2024... Excitingly, GWTC-4 could technically have been even larger, as around 170 other gravitational wave detections made by LIGO, Virgo and KAGRA haven't yet made their way into the catalog. One aspect of GWTC-4 that really stands out is the variety of events that created these signals. Within this catalog are gravitational waves from mergers between the heaviest black hole binaries yet, each about 130 times as massive as the sun, lopsided mergers between black holes with seriously mismatched masses, and black holes that are spinning at incredible speeds of around 40% the speed of light. In these cases, scientists think the extreme characteristics of the black holes involved in these mergers are the result of prior collisions, providing evidence of merger chains that explain how some black holes grow to masses billions of times that of the sun... GWTC-4 also includes two new mixed mergers involving black holes and neutron stars. [LVK member Daniel Williams, of the University of Glasgow in the U.K., said in their statement] "We are really pushing the edges, and are seeing things that are more massive, spinning faster, and are more astrophysically interesting and unusual." The catalog also demonstrates just how sensitive the LVK detectors have become. Some of the neutron star mergers occurred up to 1 billion light-years away, while some of the black hole mergers occurred up to 10 billion light-years away. Einstein's theory of general relativity can be tested with these detections, and "So far, the theory is passing all our tests," says LVK member Aaron Zimmerman, of the University of Texas at Austin. "But we're also learning that we have to make even more accurate predictions to keep up with all the data the universe is giving us." And LVK member Rachel Gray, a lecturer at the University of Glasgow, says "every merging black hole gives us a measurement of the Hubble constant, and by combining all of the gravitational wave sources together, we can vastly improve how accurate this measurement is." In short, says LVK member Lucy Thomas of the California Institute of Technology (Caltech), "Each new gravitational-wave detection allows us to unlock another piece of the universe's puzzle in ways we couldn't just a decade ago."

Read more of this story at Slashdot.

Reçu — 7 mars 2026 ⏭

Astronomers Think They've Spotted a Galaxy That's 99.9% Dark Matter

✇Slashdot
Par : EditorDavid
7 mars 2026 à 21:07
Astronomers have spotted a galaxy they believe is made of 99.9% dark matter, reports CNN — and it's so faint, it's almost invisible: CDG-2, which is about 300 million light-years from Earth, appears to be so rich in dark matter that it could belong to a hypothesized subset of low surface brightness galaxies called "dark galaxies," which are believed to contain few or no stars.... [Post-doctoral astrophysics/statistics fellow Dayi Li at the University of Toronto was lead author on a study about the discovery, and tells CNN] There is no strict definition of dark galaxies... but their existence is predicted by dark matter theories and cosmological simulations. "Where exactly do we draw the line in terms of how many stars they should have is still ambiguous, because not everything in astronomy is as clear-cut as we like," he said. "To be technically correct, CDG-2 is an almost-dark galaxy. But the importance of CDG-2 is that it nudges us much closer to getting to that truly dark regime, while previously we did not think a galaxy this faint could exist." To observe CDG-2, the researchers used data from three telescopes — Hubble, the European Space Agency's Euclid space observatory and the Subaru Telescope in Hawaii — along with a novel approach that involved looking for objects called globular clusters. "These are very tight, spherical groupings of very olds stars, basically the relics of the first generation of star formation," Li said. Globular clusters are bright even if the surrounding galaxy is not, and previous observations have shown a relationship between them and the presence of dark matter in a galaxy, Li added. Because CDG-2 appears to have very few stars, there must be something else providing the mass that the clusters need to hold themselves together. Li and his colleagues assume that the source of the mass is dark matter. The researchers found a set of four globular clusters in the Perseus Cluster, a group of thousands of galaxies immersed in a cloud of gas and one of the most massive objects in the universe. Further observations revealed a glow or halo around the globular clusters, suggesting the presence of a galaxy... Astronomers believe, Li explained, that after the formation of the clusters early in the galaxy's existence, larger surrounding galaxies stripped it of the hydrogen gas required to make more individual stars like our sun. "The material that this galaxy needed to continue to form stars was no longer there, so it was left with basically just a dark matter halo and the four globular clusters." The process, he added, would leave behind a skeleton or ghost of "a galaxy that pretty much just failed." As a result of this formation mechanism, the galaxy only has 0.005% of the brightness of our own galaxy, Li said... Studying potential dark galaxies is important because they provide nearly pristine views of the behavior of dark matter, according to Neal Dalal, a researcher at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, who was not involved with the study. Robert Minchin, an astronomer at New Mexico's National Radio Astronomy Observatory, told CNN that "it seems likely that other very dark galaxies will be found by this method in the future."

Read more of this story at Slashdot.

Reçu — 6 mars 2026 ⏭

Fausse alerte, l’astéroïde qui devait toucher la Terre, puis la Lune, passera en fait à côté

✇Numerama.com - Magazine
Par : Hugo Ruher
6 mars 2026 à 09:54

Découvert fin 2024, l'astéroïde YR4 était au centre de nombreuses spéculations car sa trajectoire avait une faible possibilité de croiser celle de la Terre ou de la Lune. Finalement, de nouvelles observations révèlent que nous sommes bel et bien à l'abri de toute collision.

Reçu — 5 mars 2026 ⏭

La Nasa a perdu une mission lunaire… Et c’est à cause d’un petit bug tout bête

✇Numerama.com - Magazine
Par : Hugo Ruher
5 mars 2026 à 13:00

Vue d'artiste du Lunar Trailblazer

La mission Lunar Trailblazer, à destination de la Lune, s'est arrêtée le lendemain de son décollage. On sait désormais pourquoi : il s'agissait d'un simple bug qui aurait pu être évité facilement.

Reçu — 4 mars 2026 ⏭

Et si ce mois-ci était le meilleur avant des années pour admirer les aurores boréales ?

✇Numerama.com - Magazine
Par : Hugo Ruher
4 mars 2026 à 12:31

En raison de l'activité solaire actuelle et de l'arrivée de l'équinoxe de printemps, le mois de mars 2026 pourrait être le meilleur moment pour observer les aurores boréales. Peut-être pas seulement dans les latitudes très élevées, mais aussi en France.

On connaît enfin le problème d’Artémis II, la NASA fixe une nouvelle date de décollage

✇Numerama.com - Magazine
Par : Julien Lausson
4 mars 2026 à 09:20

Sujette à des fuites d'hélium, la fusée SLS destinée à la mission Artémis II est en cours de maintenance. Les réparations progressent, ce qui ouvre la perspective d'un décollage du vol habité pour avril 2026.

NASA Repairs Artemis 2 Rocket, Continues Eyeing April Moon Launch

✇Slashdot
Par : BeauHD
4 mars 2026 à 07:00
NASA is eyeing an April launch window for the upcoming Artemis II mission after it repaired a helium-flow issue on the Space Launch System upper stage rocket. "Work on the rocket and spacecraft will continue in the coming weeks as NASA prepares for rolling the rocket out to the launch pad again later this month ahead of a potential launch in April," NASA wrote in an update on Tuesday. Space.com reports: The repair work occurred inside the huge Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center (KSC) in Florida. Artemis 2's SLS and Orion crew capsule have been in the VAB since Feb. 25, when they rolled back to the hangar from KSC's Launch Pad 39B. Just a few days earlier, the Artemis 2 stack successfully completed a wet dress rehearsal, a two-day-long practice run of the procedures leading up to launch. In the wake of that test, however, NASA noticed an interruption in helium flow in the SLS' upper stage. That was a significant issue, because helium pressurizes the rocket's propellant tanks. Rollback was the only option, as the affected area in the upper stage was not accessible at the pad. The problem took a potential March launch out of play for Artemis 2, which will send four astronauts on a roughly 10-day flight around the moon. It will be the first crewed flight to the lunar neighborhood since Apollo 17 in 1972. The next Artemis 2 launch window opens in April, with liftoff opportunities on April 1, April 3-6 and April 30. And those options apparently remain in play, thanks to recent work in the VAB. That work centered on a seal in an interface through which helium flows from ground equipment into the SLS upper stage. That seal was obstructing the interface, which is known as a quick disconnect.

Read more of this story at Slashdot.

Reçu — 3 mars 2026 ⏭

Du retard pour MaiaSpace, la fusée française ne décollera pas avant 2027

✇Numerama.com - Magazine
Par : Hugo Ruher
3 mars 2026 à 10:15

Vue d'artiste du minilanceur de MaiaSpace

Une fusée construite par une entreprise française devait décoller avant fin 2026, mais ce calendrier a été abandonné. La société MaiaSpace repousse l'échéance à l'année suivante, le temps de régler les derniers détails.

Reçu — 2 mars 2026 ⏭

Il y a une éclipse de Lune le 3 mars 2026… mais pourquoi n’y en a-t-il pas tous les mois ?

✇Numerama.com - Magazine
Par : Nelly Lesage
2 mars 2026 à 17:25

Le 3 mars 2026, une éclipse lunaire survient. La Lune, la Terre et le Soleil sont alors alignés. Mais comment se fait-il alors que les éclipses lunaires soient si rares ? Après tout, la Lune met environ un mois pour faire un tour de notre planète.

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